This application claims the priority of Korean Patent Application No. 10-2007-0015530, filed on Feb. 14, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a liveness detection method and apparatus, and more particularly, to a liveness detection method and apparatus which detect a real object by distinguishing a two-dimensional (2D) flat object from a three-dimensional (3D) non-flat object in a video image.
2. Description of the Related Art
Recently, many studies on biometrics have been conducted. Biometrics is widely applied to biometric authentication systems using face or iris recognition, mobile phone security, mobile commerce, physical/logical access control, e-commerce, and the like. However, no attention is paid to liveness detection.
Biometric authentication systems are vulnerable to forgery since fingerprints, irises, and faces can be easily forged. Hence, overcoming vulnerability to forgery is becoming an important issue for biometric system security. The kind of forgery described above is called ‘spoofing,’ which is carried out using a series of processes to intrude into a biometric authentication system using fake biometric samples.
Liveness detection apparatus resistant to spoofing is essential to tackle such spoofing. In particular, it is required to implement liveness detection technology using a non-intrusive method and without additional hardware.
Conventional real face detection methods are classified into a method using movements and three-dimensional (3D) technology, a user interaction method, and a method using additional hardware.
The method using movements and 3D uses a structure from motion method (SFM) in order to estimate the 3D-depth of a tracked object. This depth information is used to distinguish a real facial image from a photographed image.
The user interaction method tracks facial features and interprets a feature trajectory or a change in form. However, this method is inaccurate since the trajectory of a real facial characteristic image is similar to that of a photographed image. In addition, user manipulation is required to track features of a face, thereby causing inconvenience.
The invention disclosed in U.S. Patent No. 2005/0129286 relates to determining whether a real face has been made by examining the state of the eyes and changes of eye position. However, since conventional imaging hardware takes a photograph of an image 25 or 30 frames per second, it cannot not easily detect eye blinks. Therefore, users have to carefully change focus to meet system requirements.
The inventions disclosed in U.S. Patent Nos. 2002/0183624 and 2005/0134427 are related to the method of using additional hardware. Specifically, the invention disclosed in U.S. Patent No. 2002/0183624 uses an active-type light-emitting device in order to distinguish real samples from fake ones. While this invention is a robust algorithm and does not require user manipulation, it requires special light-emitting hardware that limits its application range. Similarly, the invention disclosed in U.S. Patent No. 2005/0134427 also requires special hardware to measure body temperature.